Final answer:
Sputum collection is specific in that it avoids contamination with saliva, focusing on lower respiratory tract secretions.
Step-by-step explanation:
Sputum collection aims to avoid saliva contamination; it targets lower respiratory specimens, unlike saliva which originates from oral structures.
To collect a sputum sample, the patient usually expectorates deep cough material into a sterile container. In contrast, to check for oral bacteria, one might gently rub a swab over the oral mucosa—the inner cheek lining—and prepare a smear on a glass slide, whose drying and heat fixing are then followed as per microbiological practices. This process is crucial in isolating specific bacteria residing in the mucosal lining rather than the more common salivary organisms.